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Resources for Communication Problems

Monday, February 25, 2008

LBT245-248思婷

LBT245-248思婷

撰寫人：9580047 王思婷

The pages：245 ~ 248

(3) Transformations of Form and Function

Closely related to Huxley’s method of studying allometric growth is D’Arcy Thompson’s (1917) famous method of transformations in which he compares related forms such as shown in Fig. 6.6 by the superimposition of Cartesian coordinates. A rectangular system is drawn over a two-dimensional representation of one form so that the distortions of the coordinates may be studied that result from drawing lines through the homologous points on the second form. This method is purely descriptive and difficult to quantify. But it illustrates the topological relationships between certain forms and how certain differences in structure may be accounted for by a single principle, usually changes in growth gradients during ontogeny. In cases where specific dimensions can be compared allometrically, we would find different values for the parameters a and b (compare Needham, 1964.on allomorphosis), of the allometric formula. In an important discussion of D’Arcy Thompson’s transformation, Woodger (1945) pointed out that the phenomenon demonstrated here must be understood in the light of genetics and embryology because no mature form can change, by a process of transformation, into any other.

However, there mat be intracellular genetic alterations such that ontogenetic histories are altered resulting in two different mature forms. The situation is diagrammed in Fig. 6.7. There are two molecular structures, Σ1 and Σ2, that are at the basis of two developmental histories H1 and H2. Σ1 and Σ2 are related to one another by the specification of a molecular transformation called Tm. The developmental histories H1 and H2, result in mature structures S1 and S2. In the case described by D’Arcy Thompson, an apparent transformation relation, Tα, persists that is characterized through the distorted coordinate systems. Notice, however, that the biological connection rests entirely in the molecular and “invisible” transformation Tmand that the apparent transformation Tα is more or less incidental—certainly not essential—for it is obvious that some or even most molecular transformations will alter the developmental histories in such a way that the corresponding two mature structure either lose their isomorphism (as in the isolated case of two-headed monsters or other deformities) or remain the same to the eyes of the unaided observer as in the case of certain inherited diseases such as hemophilia. Thus, D’Arcy Thompson transformations are probably special cases of a much more universal phenomenon.

A discussion of these transformations has some unsuspected relevance to the biological study of language, particularly the comparison of human language with animal forms of communication. We have said before that what is true of ontogeny and transformations of molecular structures is also relevant to the biological foundations of behavior because of the dependence of the latter upon the former. Thus, the emergence of a species-specific form of behavior has, essentially, a molecular transformational history. Just as in the case of mature structure, mature forms of behavior are the result of species-specific developmental histories H1 and H2, and the biological connections between any two forms of behavior must be sought for on the level of the molecular transformations Tm. What we have said of the apparent transformation Tα, holds a fortiori for the comparison of behavior.

Correspondences on this surface level will be special cases: in many more instances, all isomorphism will be lost to our eyes. We would expect mature behavior forms (that is, the homologues to S1 and S2) to vary with much greater freedom and into many more directions than gross structure, because the selection biases upon skeletal form are likely to be much more restraining than on behavioral modality, and it is also possible that epigenetic canalization (Waddington, 1956 and 1957) allows of fewer directional alternatives in the case of structural alterations than behavioral ones. Although these are speculations, it is a fact that there is greater variety in behavior among animals than in their types of Bauplan or structural pattern. In the light of this, the present thesis on the biological origins of language becomes very clear.

FIG. 6.7. Species are related to each other by transformations in molecular structure of genic material. These transformations affect the developmental histories of the animals in the course of which the original relationship may become obscured: the resulting mature structure may or may not bear resemblance to one another.

We assume that our potential for language has a biological history that is written in terms and on the level of molecular transformations Tm; but this belief commits us in no way to expect the occurrence of apparent transformations Tα. If human language be S2, we cannot even be sure, in fact, what may be token of S1. Similarly, if a superficial resemblance is pointed out to us between language and some behavioral aspect of another species, we cannot be certain how close or distant the underlying relationship Tmactually is, or for that matter, if there is any such relationship whatever. Because modifications of behavior may be freer and go into many more directions than modifications of structures, molecular transformations Tm may leave in many fewer cases apparent transformations Tα than is the case for skeletal structure and thus there is the danger of being misled by similarities that are in fact not objective but that are entirely due to anthropomorphic interpretation of animal’s activities. (Examples of this are not restricted to animal “language” but may be found in statements about animal “play”, or animal “families”, or animal “pleasures.”)

The transformational picture leads us to expect that molecular alterations indirectly caused changes in the temporal and spatial dimensions of the species’ developmental history and that the resulting alterations in structure and function brought with them prolonged and changed periods during which one function could be influenced by others, thus creating critical periods of special sensitivities and opening up new potentials and capacities. This is just the framework within which we would like to see our thoughts move; it is too vague to be a theory. Let us look at it as the direction for possible explanations that are yet to come.

Ⅲ. EVIDENCE FOR INHERITANCE OF LANGUAGE POTENTIAL

The inheritance of behavioral traits in man can never be definitively demonstrated because of our inability to do breeding experiments. Also, absolute control of the environment is difficult to achieve. If we are staunch believers in the sole determination of behavior by the social environment was held constant. It is always possible to argue that there might have been subtle differences in human relations so that even two individuals who are raised in the same home might have experienced different treatment, invisible to the observer, and that all differences in behavior might be due to these variations. Similar but converse arguments are also possible in the case of identical behavior in apparently different environments.